Make a hard state change from catchup to streaming mode.

More useful state change for monitoring purposes, plus a
required change for synchronous replication patch.

diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index e04d59e..eb99246 100644 (file)
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -369,6 +369,16 @@ StartReplication(StartReplicationCmd * cmd)
                                (errcode(ERRCODE_CANNOT_CONNECT_NOW),
                errmsg("standby connections not allowed because wal_level=minimal")));
 
+       /*
+        * When we first start replication the standby will be behind the primary.
+        * For some applications, for example, synchronous replication, it is
+        * important to have a clear state for this initial catchup mode, so we
+        * can trigger actions when we change streaming state later. We may stay
+        * in this state for a long time, which is exactly why we want to be
+        * able to monitor whether or not we are still here.
+        */
+       WalSndSetState(WALSNDSTATE_CATCHUP);
+
        /* Send a CopyBothResponse message, and start streaming */
        pq_beginmessage(&buf, 'W');
        pq_sendbyte(&buf, 0);
@@ -752,8 +762,17 @@ WalSndLoop(void)
                                break;
                }
 
-               /* Update our state to indicate if we're behind or not */
-               WalSndSetState(caughtup ? WALSNDSTATE_STREAMING : WALSNDSTATE_CATCHUP);
+               /*
+                * If we're in catchup state, see if its time to move to streaming.
+                * This is an important state change for users, since before this
+                * point data loss might occur if the primary dies and we need to
+                * failover to the standby. The state change is also important for
+                * synchronous replication, since commits that started to wait at
+                * that point might wait for some time.
+                */
+               if (MyWalSnd->state == WALSNDSTATE_CATCHUP && caughtup)
+                       WalSndSetState(WALSNDSTATE_STREAMING);
+
                ProcessRepliesIfAny();
        }